A hash algorithm is a function which takes a variable size input and produces a fixed size output. The algorithm tries to make it difficult to predict the output for a given input, find two inputs with the same output, or reconstruct the input from the output.

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Should we start using SHA-3? [duplicate]

Possible Duplicate: What is SHA-3 and why did we change it? SHA-3 has been finalized! So, what does secuirty.se think about the new hash funciton? Should we start replacing all uses of ...
28
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4answers
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What is SHA-3 and why did we change it?

On the 2nd of October NIST decided that SHA-3 is the new standard hashing algorithm, does this mean we need to stop using SHA-2 as it is not secure? What is this SHA-3 anyway?
3
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2answers
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Program binaries or files with same MD5 hash

I'm looking for 2 different program binaries or 2 different files with the same MD5 hash to prove its weakness and the collisions in the algorithm.
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5answers
624 views

What about combining pkdf2 with scrypt? [duplicate]

Possible Duplicate: Would it make sense to use Bcrypt and PBKDF2 together? How does the following password hashing scheme look to you? iterations1 = scrypt iterations required to spend ...
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3answers
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Are there flaws in this simple key exchange?

I'm reviewing for a computer security exam. Here is a simple scenario: Suppose that someone suggests the following way to confirm that the two of you are both in possession of the same secret key. ...
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1answer
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PHP crypt() trims the salt as it would be too long

I am using Blowfish with PHP crypt() for password hashing but I noticed something weird. Quoting PHP documentation: CRYPT_BLOWFISH - Blowfish hashing with a salt as follows: "$2a$", "$2x$" or ...
4
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2answers
838 views

What is the purpose of using Youtube-style alphanumeric ids as URL slugs?

I asked a question on StackOverflow on how to generate the alphanumeric/base64 resource IDs that Youtube, Instragram, and others use to identify videos/pictures/etc. Discussion led to the question of ...
5
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3answers
3k views

bcrypt: random salt vs computed salt

I'm pretty new to the whole password hashing business, so I might be missing something obvious. I was looking at the bcrypt algorithm, in particular BCrypt.Net, and I was wondering if it wouldn't be ...
12
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1answer
2k views

Insecure versions of crypt hashes

I read at crackstation not to use these variants of bcrypt* ($1$, $2$, $2a$, $2x$, $3$),but I've used bcrypt ($2a$) in various sensitive implementations recently. Can any security expert clarify why ...
4
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1answer
80 views

Standards for CA cert revocation and time-constrained cryptographic algorithm parameters

I'm working on software that will be in use for foreseeable future (15 years+) that will need to validate XAdES-A signatures (long term archival, similar to PAdES-A, but for XML). That means, it will ...
2
votes
3answers
2k views

Proper hash_hmac key creation

I'm looking for, but unable to find, some definitive information on how long to make the secret and what characters are useable in creating a HMAC signature in PHP using SHA256. I found some ...
3
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1answer
363 views

DPAPI offline attack by cracking windows password?

I'm thinking of using DPAPI to protect configuration file information in my program. After doing some reading on it, it looks like it uses the user's Windows password as part of the encryption ...
1
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1answer
295 views

Can I combine two of SHA-3 candidates cryptography hash functions and obtain more secure Algorithm? [duplicate]

Possible Duplicate: Are different hash algorithms ever used together? For example, Is possible to combine (Concatenate or Chain or XOR) Skein SHA-3 candidate with Grostl SHA-3 candidate to ...
7
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1answer
1k views

Identifying an unknown hash

During some of my research work I encountered an unknown hashed string. What I am curious about is the algorithm used to generate it. A factor that makes it interesting - the string contains an ...
10
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2answers
3k views

Estimating the size of a rainbow table

What are rainbow tables and how are they used? Gives a very precise answer about what rainbow tables are and how they are used. I had always confused hash-tables and rainbow tables. My question is ...
17
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6answers
15k views

Is MD5 considered insecure?

After all these articles circulating online about md5 exploits, I am considering switching to another hash algorithm. As far as I know it's always been the algorithm of choice among numerous DBAs. Is ...
1
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0answers
190 views

Recomended hash algorithm [duplicate]

Possible Duplicate: How to securely hash passwords? Do any security experts recommend bcrypt for password storage? What would you choose between: PBKDF2 SHA256 (270,000 iterations) ...
3
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2answers
487 views

Scrypt + Bcrypt = cascade hashing

I've read here that hashing with differents algorithms would be a good idea. Can you confirm that? In your experience, is it useful and safe? Does it entail any security holes?
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1answer
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Is PBKDF2 only SHA1 in C#?

I can't find a way of specifying the hashing algorithm used by the PBKDF2 (the Rfc2898DeriveBytes class) implementation in C# System.Security.Cryptography. It seems to be just SHA1. Am I missing ...
3
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2answers
568 views

Implementing brute force attacks on hash values in Javascript

I'm working for my bachelor thesis at the end of which I aim to implement a proof-of-concept Javascript-based hash cracker. The idea is to work like this: Users can submit a hash value along with ...
37
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3answers
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Is SHA1 better than md5 only because it generates a hash of 160 bits?

It is well known that SHA1 is recommended more than md5 for hashing since md5 is practically broken as lot of collisions have been found. With the birthday attack, it is possible to get a collision ...
52
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3answers
31k views

Securing a JavaScript Single Page App with RESTful backend

I'm currently in the process of building a JavaScript SPA and have been researching how to secure it. There is currently as RESTful API that is being completely interacted with through AJAX. We also ...
6
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2answers
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Production ready bcrypt implementation for .NET

Which, if any, .NET / C# bcrypt implementations are considered suitable for production environments? I have seen CryptSharp and BCrypt.Net mentioned in answers to other questions but without any ...
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5answers
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making an iPhone/Android app which sends a user password to my server, how to secure?

I'm making an iPhone/Android app for my website, users already have an account on the website and the app will allow them to login. I don't have SSL on my website, but it's just a reviews website and ...
3
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1answer
122 views

Password hashing on a load balancing setup

I've been doing some research into password hashing implementations and would like to know if it's feasible to have two servers hash passwords to the same database? I've come across the Bcrypt.net ...
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1answer
754 views

Please tell me two strings which have the same MD5 hash value

Yes, I know MD5 is weak and should not be used. To make a prove of concept I need two strings with the same MD5 value but all I can find is binary. Like this nice example. Works fine as binary but ...
19
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6answers
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Hash function change

I have user account passwords stored in a database using an unsafe (old) cryptographic hash function. What is the best/usual approach to changing password hash function? Only two ideas come to my ...
2
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1answer
712 views

What kind of hashing is generally used in log-in modules?

Do operating systems hash the log-in password? What hash function is used in Windows XP, 7, 8,Linux Ubuntu, Debian, MAC Lion OS X ,...? Where should I look to know these security considerations of an ...
6
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3answers
442 views

How can Microsoft validate a shorter password on Microsoft accounts (MSDN)?

I recently ran across this when logging into MSDN. (I saw this screen after typing my initial credentials.) I have a 20+ digit password, however there's apparently a new requirement for Microsoft ...
7
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3answers
489 views

How secure is HTTPS with weak ciphersuites?

Today I came across the website https://mtgox.com/, which claimed to be secure because of the Verisign certificate. I checked the certificate out of curiosity (it's the first thing they claim, let's ...
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2answers
125 views

Should I use salt to authenticate data?

I have a client and a server. The client makes a request containing userId, cardId, position (on the card) A hacker could just do the same http request with the next position. So I think about ...
5
votes
3answers
331 views

What steps can you take to make offline cracking of SRP harder?

In the aftermath of the Blizzard hack, what steps can I take to make offline cracking of SRP more difficult? My question assumes that your database is already gone and that you implemented SRP more ...
5
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6answers
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Tracking unique web site visits without logging IP addresses

On Monday, some IP address xxx.xxx.xxx.xxx visits my site. I log it. On Tuesday, another IP address yyy.yyy.yyy.yyy visits my site. I log it. If the two IP addresses are equal, I throw out the ...
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3answers
315 views

For what do I hash user passwords with PDKDF2 when the user data is stored in the same database?

I'm hashing the passwors of my users with PDKDF2 right now. A user can gain access to his account with his password. When the user is logged in he can edit his personal information and do other stuff ...
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4answers
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How secure is the SRP that Blizzard uses to protect passwords?

Blizzard very recently announced that their network was compromised, but they assure users in their statement that the password information that the attackers had access to was saved in a secure way: ...
7
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8answers
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Does truncating the cryptographic hash make it impossible to crack?

I store password hashes in their full value for example, $h = sha256('foo') outputs 64 characters: 2c26b46b68ffc68ff99b453c1d30413413422d706483bfa0f98a5e886266e7ae I store that directly in the ...
3
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6answers
309 views

Is it okay to wrap a cryptographic hash with MD5 for storage?

Is there any security issues if you wrap your cryptographic hash with MD5 for storage purposes? For example: $hash = md5(hash($password,$salt,$rounds)); Note: hash() uses scrypt or bcrypt or pbkdf2 ...
7
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4answers
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Is sha-1 hash always the same?

Is it possible to ensure that a string is hashed always the same way no matter which language you use to do it (Java, vb.net... ) and no matter what operative system you are?
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1answer
756 views

Global salt vs salt-per-password [duplicate]

Possible Duplicate: Password Hashing add salt + pepper or is salt enough? Any risk in using the same salt for several hashes on a user? It's known that all password hashes need to be ...
1
vote
1answer
1k views

How many possibilities can today's computers check (per second) in a SHA512 hash of a 50-byte-long random entry? [closed]

The problem I want to avoid is "brute force" attacks against a database. So if I add a 50-byte-long cryptographically random salt to my information (which I don't need to retrieve, just its hash) - is ...
3
votes
1answer
199 views

How should I store a password to allow people to enter single characters from it? [duplicate]

Possible Duplicate: How do some sites (e.g. online banks) only ask for specific characters from a password without storing it as plaintext? Some banking applications ask for random letters ...
2
votes
2answers
2k views

Is there an index of all md5 collisions?

I am about to build a caching system based on md5 to generate file names out of lists of natural numbers. The inputs would be groups like: 1,18,94,100,266,1854. I know there are some collisions in ...
8
votes
2answers
740 views

Is there more to password hashing?

You have a plain text password and salt. The plain text password is assumed to be securely random and only known by the user and the salt is no secret and not necessarily unique but stored alongside ...
13
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2answers
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With PBKDF2, what is an optimal Hash size in bytes? What about the size of the salt?

When creating a hash with PBKDF2, it allows the developer to choose the size of the hash. Is longer always better? Also, what about the size of the random salt? Should that be the same size as the ...
1
vote
1answer
105 views

How to verify that a clientside-generated object is genuine?

I know that general best-practice states not to trust anything generated by the client. With that in mind, I want to write an HTML5 app that utilises the browser to generate various objects ...
63
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5answers
22k views

Is sending password to user email secure?

How secure is sending passwords through email to a user, since email isn't secured by HTTPS. What is the best way to secure it? Should i use encryption?
5
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2answers
464 views

Can a HSM be used to make password hashing stronger?

Say a database server has a HSM which is in use for encrypting (reversibly of course) credit card numbers. Is there any way a HSM could be used to add strength to a password hashing scheme? (Or are ...
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votes
2answers
370 views

How to secure passwords when site is opensource [duplicate]

Possible Duplicate: How to securely hash passwords? How can I store passwords to have them secure? Right now the site use md5 md5, I was thinking about sha1+salt but if the source code for ...
8
votes
4answers
700 views

How can we factor Moore's law into password cracking estimates?

How would we go about factoring Moore's law into exceedingly long password cracking estimates? Let's say we've got a 12 character password containing mixed-case alpha characters and numbers, i.e. ...
6
votes
3answers
20k views

Windows 7 Password Hash Security

I recently came across a number of sources that suggest that cracking Windows user account passwords is easy by examining their password hashes. I understand that these hashes are stored in the SAM ...